The whole conundrum of “choosing an instance” is a phase that early adopters like us go through. People can’t be expected to go through the choosing part, then find communities to follow.
You don't necessarily need to. Here you can just send somebody a link to an instance. But this should not be the case for communities.
I agree with you that the dezentrality should be hidden as much as possible - but first: how do you explain to such a person all the other communities on the community tab? Second: If the frontend is designed well (almost as it currently is, just with the different default setting I suggested), you can browse through communities of other instances AS IF they were on your own instance. The thing that the choice of the instance decides should be technical stuff, moderation standards and the instances (ergo the communities) you see.
More generalised communities like lemmy.world means we keep trying to build a centralised alternative to Reddit.
No. You are turning the whole idea of the fediverse upside down. The dezentrality is there for tech and architecture but not for content. What YOU suggests points to a gated community just as big techs wants it. Sure, choosing an instance should maybe be jumped over when joining the threadiverse but the aspect of dezentrality should, even if it only abstracted, be an aspect of the user experience from the beginning. Maybe then people realize what instances actually are after a while but I'm not a fan of creating first a "sandbox" where they can experience the threadiverse as if it where a centralized platform to later join the "real" threadiverse and learn everything about dezentralization, choosing your instance etc because too often they stay there.
The problem about lemmy.world is that it is too big - but how should other instances grow if all the user focus is directed to internal communities?
The local feed is what differentiates an instance. The quality of which is a direct indicator of the instance’s quality. Hence the most important feed
The all-feed does so too given which instances they mute. I think currently Lemmy does not have really good moderation tools but that doesn't change the fact that the quality of All is also determined by the instance you are on.
The ultimate end user doesn’t even need to know what Lemmy is.
So if they start on an Arsenal lemmy instance they think about lemmy as a social network about Arsenal? And you would be ok with that and even consider it a user-behavior that should be encouraged? I'm sorry if I sound too harsh but that's just not I have in mind there.